JPS59106882A - Protecting device for air conditioner with inverter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an inverter-equipped air conditioner that protects an inverter output element section of the inverter-equipped air conditioner from overcurrent.

FIG. 1 is a block diagram showing a protection device for an air conditioner equipped with an inverter. In FIG. 1, reference numeral 1 denotes an AC power source, and a converter section 2 is connected to this AC power supply 1 to temporarily convert AC power into DC power. This DC power passes through a current detection resistor 3 to an inverter output element section 5.
is supplied to.

Transistors are generally used as the elements of this inverter output element hIS5, and by turning on or off each transistor in a predetermined order by the inverter control unit 4, three-phase output current is obtained and the compressor motor 6 I try to let it flow.

With this configuration, the compressor motor 6 is controlled by the inverter output element section 5 according to the command issued by the inverter control section 4.
Since the output element (transistor) of the compressor motor 6 is turned on and off as appropriate and driven by variously variable frequencies, the rotational speed of the compressor motor 6 can be varied in various ways.

Therefore, since the rotation speed of the compressor (not shown) connected to the compressor motor 6 also changes, the capacity can be varied accordingly.

In addition, when the compressor locks and the compression protection motor 6 stops, the current flowing through the compressor motor 6 increases, so the current flowing through the current detection resistor 3 also increases, and the current flowing through the current detection resistor 3 also increases. Since the voltage drop will also increase, input this voltage to the inverter control unit 4, and if the inverter output element unit 5 is likely to be destroyed, first control the inverter so that the frequency is lowered when it reaches a certain level. A command is issued from the inverter output element part 4 to the inverter output element part 5 to control the compressor motor 6 to reduce the required current, but if the current increases further, a 0 frequency command is sent from the inverter control part 4 to the inverter output. It outputs to the element section 5, cuts off the current to the load, and makes the current zero.

In this way, the elements of the inverter output element section 5 are protected from flowing excessive current through the cords.

The reason why this element is destroyed is because current flows through the element and the element becomes high temperature, causing thermal destruction. Therefore, the ambient temperature must be taken into account, and the detection current level of Hitomi Kagamiru is at the maximum ambient temperature. Even if there is, it is selected directly so that it can be sufficiently protected, so it has enough protection against normal ambient temperatures.

Normally, in the case of inverters used in general equipment, the temperature difference between the highest and lowest temperature is about 40'C, and the work required by the load does not vary much, but in the case of air conditioners, the temperature difference is around 40'C. The temperature will be around 80℃, and when considering heating operation, when the ambient temperature is high, a large amount of work is not required, but when the ambient temperature is low, a large amount of work is required, so the amount of work increases. It has become.

Therefore, in such a case, if the current value is set to a value that provides sufficient protection at high temperatures, there is a drawback that sufficient work cannot be done when the ambient temperature is low.

On the other hand, if the current value is set to a value that allows sufficient work to be done at low temperatures, when the ambient temperature rises, too much current will flow and the device will be destroyed.

The above 6-mei was made to improve this point, and it detects the temperature of the output elements of the inverter output element section or the outside air and adjusts the value of the protective current so that the current flows to the maximum that the output elements can flow. It is an object of the present invention to provide a balance maintenance device for an air conditioner equipped with an inverter, which can vary the temperature depending on the temperature and can sufficiently exhibit its performance with a relatively small capacity output cable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a protection device for an auxiliary machine with an inverter according to the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing the configuration of one embodiment.

In FIG. 2, in order to avoid duplication, parts that are the same as those in FIG. 1 will be given the same reference numerals and their explanations will be omitted, and parts that are different from those in FIG. 1 will be mainly described.

As is clear from comparing this Figure 2 with Figure 1,
In the figure, parts indicated by numerals 1 to 6 are the same as in Fig. 1;
This invention differs from FIG. 1 in that a temperature detection section 7 is newly provided.

That is, this temperature detection section 7 is connected to the inverter output element section 5.
The temperature of this output cable is detected and the detected output is sent to the inverter.
It is designed to be sent to both departments 4.

Next, the operation of the inverter-equipped air conditioner protection device of the present invention configured as described above will be explained. The converter 2 smooths the AC power inputted from the AC electric power 1 by means of a wind current circuit composed of diodes, capacitors, etc., and obtains a DC force on the output side.

This output is supplied to the inverter output element section 5 via the current detection resistor 3. The output elements of this inverter output element section 5 are generally made up of six transistors, and three-phase output power is obtained by interrogating two bares each with a delay of 120 degrees in electrical angle. .

The base inverter control unit 4 of this transistor sends appropriately delayed signals to control the transistor 1.

Further, a temperature detection section 7 is brought into close contact with the output element, and the temperature of this output element is detected and a detected output is sent to the inverter control section 4.

Therefore, in the inverter open side 1 section 4, when the load becomes heavy and the required current of the compressor motor 6 starts to increase, the required current is also detected and applied to the inverter control section 4, and the inverter control section 4 The operating point can be changed by the output detected by the detection unit 7 and the voltage across the current detection resistor so that protection is activated within the tolerance limit of the output element relative to the ambient temperature.

By doing so, a larger current can be drawn when the ambient temperature is low, and in the case of heating with an air conditioner, a larger capacity can be obtained than in winter, which is advantageous.

It should be noted that in order to change the protection point of the detected current, it may be configured with a comparator and an analog switch element, or of course may be processed using software using a microcomputer or the like.

Furthermore, in an air conditioner, it is unlikely that the outside temperature will suddenly change, so the same effect can be obtained by detecting the temperature by using the outside temperature instead of the output element.

As described above, according to the protection device for an air conditioner with an inverter of the present invention, the value of the protective current is set such that the output element of the inverter output element portion or the outside air temperature is detected and the current flows up to a maximum of 1 hour as required by the output element. By making it possible to vary the output power depending on the temperature, it is possible to increase the output power when the temperature is low without increasing the rated power of the output element, and it is also possible to generate sufficient hQ force using an output element with a relatively small capacitance. I can demonstrate it.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional protection circuit for an air conditioner equipped with an inverter, and FIG. 2 is a block diagram of an embodiment of the protection circuit for an air conditioner equipped with an inverter according to the present invention. 1... double current power supply, 2... con-9-evening, 3...
Current detection resistor, 4... Inverter control section, 5... Inverter output element section, 6... Compressor motor, 7...
・Temperature detection section. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno - Figure 1 Figure 2

Claims (3)

[Claims] (1) A converter section that converts alternating current power into electrical power;
an in/9-inverter output element section that converts the converter section into alternating current power to drive the compressor motor; a first means connected between the converter section and the inverter output element section that detects a load current;・Temperature detection unit that is in close contact with the output element of the inverter output element unit and detects its temperature or detects the outside temperature, and when the value detected by the first means exceeds a predetermined value, the inverter output element unit Lower the frequency of the AC power output from the temperature sensor or set it to zero frequency, and if the detected value detected by the temperature detection section is low, protection will work with high current, or if the detected value is high, protection will work with low current. An inverter comprising a second means for controlling the inverter output element section so as to change the protection point of the output element as shown in FIG.
Tagged sky ii1. II aircraft protection device. (2) The protection device for an air IS aircraft equipped with an inverter according to claim 1, wherein the second means changes the protection point of the stain flow by a comparator and an analog switch. (3) The second means inputs the output of the first means and the output of the temperature detection section using a microcomputer and processes the input according to a program.
Protective device for air conditioners with inverters as described in .